--- zlib-1.2.12/inflate.c.old	2022-08-09 10:30:18.831225181 +0000
+++ zlib-1.2.12/inflate.c	2022-08-09 10:29:33.251225181 +0000
@@ -792,8 +792,9 @@ int flush;
                 if (copy > have) copy = have;
                 if (copy) {
                     if (state->head != Z_NULL &&
-                        state->head->extra != Z_NULL) {
-                        len = state->head->extra_len - state->length;
+                        state->head->extra != Z_NULL &&
+                        (len = state->head->extra_len - state->length) <
+				state->head->extra_max) {
                         zmemcpy(state->head->extra + len, next,
                                 len + copy > state->head->extra_max ?
                                 state->head->extra_max - len : copy);